Remember when we previously identified exactly what the protective power of the Pfizer vaccine against COVID-19 was?

CNBC reported on the newest data provided by the Israeli Ministry of Health on July 23, 2021, which are doubly concerning. According to the investigation, the Pfizer/BioNTech mRNA vaccine provides only 39% protection against infection with symptomatic COVID-19 caused by the Delta mutant strain in Israel. Accordingly, Israel began the third dose of administration as a booster to its nationals as of July 30.

Meanwhile, the New England Journal of Medicine (NEJM) published the first real-world study data obtained from the UK Public Health Department (PHE) on the protective efficacy of vaccination against the Delta on July 21, 2021. The Pfizer mRNA vaccine demonstrated 88% protection against symptomatic COVID-19 infection caused by the Delta mutant strain.

Both values are correct, and an in-depth analysis of the data behind them reveals that reduced vaccine protection occurs due to/among:
* Extended duration of vaccination.
* The elderly group.

The timing of vaccination in the UK and Israel data is radically different, as is the proportion of elderly people, hence the results produced are inherently different. However, it is worth considering that:
1. Did the Delta mutant strain reduce the vaccine's efficacy?
2. Will the vaccine still protect us six months later?

On October 4, 2021, a study of more than 3.4 million people by US academics entitled "Effectiveness of mRNA BNT162b2 COVID-19 vaccine up to 6 months in a large integrated health system in the USA: a retrospective cohort study" was published in the Lancet, revealing that:
1. A reduction in protection against infection after Pfizer vaccination from 88% to 47% at 5 months.
2. The decline in protection against infection by the vaccine was due to a decrease in immune antibodies over time, rather than evasion of the vaccine by the Delta mutant.
3) After 5 months of full vaccination with Pfizer vaccine, the protection against COVID-19 hospitalization/death remained at 88%.

Data for this study were gathered from the electronic health records of Kaiser Permanente Southern California, a healthcare organization in California, USA, between December 14, 2020, and August 8, 2021. A total of 3,43,957 subjects were included, with 52.4% female. All were aged 12 years and older, with a median age of 45 years. This group received the BNT162b2 mRNA vaccine from Pfizer-BioNTech, which is also one of the top three most effective vaccines ever developed.

SARS-CoV-2 continues to mutate and alternate to attack humans until the most infectious mutant strain, the Delta mutant was screened out, making it one of the three most infectious viruses in human history. The Delta mutant strain firstly appeared in California in April, although it accounted for barely 0.6% of the total. However, by June, Delta accounted for more than half of the population, and in July the Delta mutant became the absolute dominant strain (86.5%).

* The protection against COVID-19 infection was 88% one month after completion of vaccination, including 80% in individuals of 65 and older. The resistance against the Delta mutant strain was 93%.
* At 5 months of complete vaccination, the protection of the vaccine against infection with COVID-19 decreased to 47% and 43% in elderly people aged 65 years and older. Among them, the protection against the Delta mutant strain was 53% (at 4 months).
* Within 1 month of complete vaccination, the protection against severe/morbid COVID-19 was 87%, with 93% protection against infection with the Delta mutant strain.
* At 5 months of complete vaccination, the protection against severe illness and death was 88%, virtually unchanged. American medical scientists believe that humans need to abandon the practice of relying on universal vaccination boosters to prevent infection since they cannot protect against Delta mutant strains. Instead, efforts should be focused on preventing severe illness and death, but the current vaccine is sufficient to accomplish this task of preventing severe illness, so only vulnerable and susceptible populations need to be paid attention to.

It is also due to the emergence of the Delta mutant strain that the hopes of human beings to clear COVID-19 through vaccination have almost been dashed and a "new normal life with a new coronavirus" has to be accepted, i.e., no more overemphasis on prevention of infection, but rather on prevention of severe illness and death.

According to data from Los Angeles, USA, the rate of severe illness was 3.2% and death was reduced to 0.2% after complete vaccination. The just-released oral antiviral drug from Merck reduced the rate of severe illness by 50% in high-risk infections and no deaths in the treatment group (8 deaths in the placebo group). A return to a new normal life can be expected through a model of vaccination prevention plus oral antiviral treatment.